ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1aAO8. Use of simplified coupled mode propagation for the prediction of impulse responses of megameter trans-Arctic propagation paths.

Herbert A. Freese

Sci. Applic. Int. Corporation, McLean, VA 22102

In the spring of 1994, a long-range propagation experiment was conducted in the Arctic during which large time-bandwidth product signals (M sequences) were transmitted to two receiver sites. These data were processed to extract the pulse response of the propagation channel at the vertical arrays at each site and a horizontal array at one of the sites. These data are being used for an assessment of the utility of Arctic acoustic measurements for global warming signature detection and monitoring. A critical part of this measurement is the identification of the observed paths with specific propagating modes. A method has been developed based on coupled normal modes which allows us to estimate pulse responses quickly. The results agree favorably with the experimental data when historical environment data are used as the model inputs. The modeling methods used, comparisons with the measurements and implications, as well as the impact on sound speed accuracy required, will be discussed.